Magnesium decaborane tetrahydrofuran adduct



Patented Feb. 11, 1964 3,121,097 MAGNESlUM DECABORANE TETRAHYDRO- FURAN ADDUUI lolm W. Ager, In, Buifnlo, N.Y., assi' nor to Olin Winthroson Chemical Corporation, a corporation of Virgnna No Drawing. Filed Sept. 30, 1958, Ser. No. 764,451 2 Claims. (Cl. 260-3461) This invention relates to preparation of the new adduct, nagnesium decaborane tetrahydrol'uran,

Mg lO l3 2 A E vlore in particular, this invention relates to the ireparation of the magnesium decaborane tetrahydrouran adduct by heating a tetrahydrofuran solution of a nagnesium decaborane ammonia adduct of the kind decribed in my copending application Serial No. 764,455, iled of even date herewith. That copending application lescribes the preparation of magnesium decaborane amnonia adducts by the direct reaction of magnesium and lecaborane while they are dissolved in liquid ammonia It a temperature of from 60 C. to +40 C., elevated aressures being employed when needed to keep the amnonia in liquid phase.

The magnesium decaborane adducts prepared by the nethod of this invention can be incorporated with suitlble oxidizers such as ammonium perchlorate, potassium erchlo-rate, sodium perchlorate, lithium perchlorate, rlurninum perchlorate, ammonium nitrate, etc., to yield 1 solid propellant suitable for rocket power plants and )ther jet propelled devices. Such propellants burn with iigh flame speeds, have high heats of combustion and are of the high specific impulse type. These magnesium iecaborane adducts when incorporated with oxidizers are :apable of being formed into a wide variety of grains, :ablets and shapes, all with desirable mechanical 1nd chemical properties. Propell ants produced by the nethods described in this application burn uniformly without disintegration when ignited by conventional neans, such as a pyrotechnic type igniter, and are nechanically strong enough to withstand ordinary han iling.

The following example illustrates the invention.

EXAMPLE In this example, 2 grams (0.0165 mole) of dec aborane and 0.17 gram (0.0071 mole) of magnesium turnings were placed in a 250 ml. three-neck flask. The flask was connected to a fraction cutter of 100 ml. capacity and a Dry-Ice cold finger condenser. The apparatus was swept with nitrogen and the reactants heated to incipient melting of the decaborane. After the mixture had cooled to room temperature, 50 ml. of ammonia gas was condensed in the graduated tube of the fraction cutter. Then the liquid ammonia was transferred to the reaction flask which was cooled with Dry-Ice. The color of the decaborane magnesium mixture immediately changed to yellow. Eflervescence and solution of the magnesium proceeded for approximately one hour in the presence of the refluxing ammonia. Then the ammonia was allowed to evaporate. A dry, white solid residue remained in the flask. No unreacted magnesium was visible.

The white solid residue was washed with ether, filtered and then dissolved in about ml. of tetrahydrofuran. Ammonia evolved, and the tetrahydrofuran became yellow. A white solid was also obtained. This mixture was refluxed for a few minutes until ammonia evolution ceased and the tetrahyclrofuran distilled. The yellow product was washed with ether and dried.

An infrared spectrum of the yellow product showed practically no similarity to that of the magnesium decaborane ammonia adduct. The spectrum contained strong OH bands and appeared to have some basic dec aborane structure. Two elemental analyses of the product showed that it contained 44.3, 44.0 percent boron, 4.15, 3.94 percent magnesium, 13.13, 12.47 percent carbon and 9.50, 9.79 percent hydrogen. These analyses indicate one tetrahydrofuran molecule to two deca boranc molecules, hig(B1gH13)gC4HflO.

The boron-containing solid material produced by practicing the method of this invention can be employed as an ingredient of solid propellant compositions in accordance with general procedures which are well-understood in the art, inasmuch as the solids produced by practicing the present process are readily oxidized using conventional solid oxidizers, such as ammonium perchlorate, potassium perchlorate, sodium perchlorate, ammonium nitrate and the like. In formulating a solid propellant composition employing these magnesium decaborane products, generally from 10 to 35 parts by weight of boron-containing material and from to parts by weight of oxidizer, such as ammonium perchlorate, are present in the final propellant composition. In the propellant, the oxidizer and the product of the present process are formulated in intimate admixture with each other, as by finely subdividing each of the materials separately and thereafter intimately admixing them. The purpose in doing this, as the art is aware, is to provide proper burning characteristics in the final propellant. In addition to the oxidizer and the oxidizable material, the final propellant can also contain a binder such as an artificial resin, generally of the ureaformaldehyde or phenolformaldehyde type, or an artificial rubber like substance, the function of the binder being to give the propellant mechanical strength and at the same time improve its burning characteristics. Thus, in manufacturing a suitable propellant proper proportions of finely divided oxidizer and finely divided magnesium decaborane product can be admixed with a suitable hinder, the proportions being such that the amount of the binder is about 5 to 10 percent by weight, based upon the weight of the oxidizer and the magnesium decaborane product. The ingredients are thoroughly mixed and following this the mixture is molded into the desired shape, as by extrusion. Thereafter, the binder can be cured by resorting to heating at moderate temperatures. For further information concerning the formulation of solid propellant compositions, reference is made to US. Patent No. 2,622,277 to Bonnell et a1. and US. Patent No. 2,646,596 to Thomas et al.

I claim:

1. A method for the preparation of a magnesium decaborane tetrahydrofuran adduct which comprises forming a tetrahydrofuran solution of a magnesium decaborane ammonia adduct, heating the solution until ammonia evolution substantially ceases, and separating a magnesium decaborane tetrahydrofuran adduct from the resulting solution.

2. An adduct of the formula Mg(B H -C H O.

No references cited. 

1. A METHOD FOR THE PREPARATION OF A MAGNESIUM DECABORANE TETRAHYDROFURAN ADDUCT WHICH COMPRISES FORMING A TETRAHYDROFURAN SOLUTION OF A MAGNESIUM DECABORANE AMMONIA ADDUCT, HEATING THE SOLUTION UNTIL AMMONIA EVOLUTION SUBSTANTIALLY CEASES, AND SEPARATING A MAGNESIUM DECABORANE TETRAHYDROFURAN ADDUCT FROM THE RESULTING SOLUTION. 